1. Field of the Invention
The present invention relates to a base member on which a plurality of members are mounted, and to a method for manufacturing this base member, and further relates to a motor, an information apparatus, and methods for manufacturing them.
2. Background Information
For example, a hard disk drive (HDD) comprises a spindle motor, a recording disk attached to the spindle motor, a head for reproducing data from the recording disk or recording data to the recording disk, and an actuator for driving the head.
The spindle motor and actuator of a hard disk drive are mounted on a base plate. The base plate is, for example, a member obtained by subjecting a blank obtained by aluminum die casting to precision machining with a machining center or the like. Structures are formed in the base plate, such as the shape of ribs provided to the blank, the attachment portion of the actuator, and the screw portion for component attachment, and the shape of these structures vary with the model of the hard disk drive. The reason is that the specifications of the attached components vary with differences in the number of disks, the rotating speed, the intended application, and so forth.
Meanwhile, between models of the same form factor (such as 2.5-inch) from the same hard disk drive manufacturer, the shapes are very similar, making it difficult to tell at a glance the difference between the shapes of the above-mentioned structures. Consequently, a blank is sometimes accidentally supplied to a machining center corresponding to a different model. When this happens, the blank ends up being precision machined by a machining program corresponding to a different model. In such a case it is hard to notice that the product is irregular, and this accidentally machined base plate may continue on to the next production line without being detected. This can result in the base plate ending up in a completed hard disk drive, and may not be detected until the shipping inspection step. As a result, after the shipping inspection step, the completed product has to be discarded or reassembled.
Therefore, a mark is formed to identify the model of the base plate. For instance, there is a known technique whereby a plurality of display holes indicating a manufacturing die number are formed in a base plate (see Japanese Laid-Open Patent Application 2001-101777, for example). However, with the technique discussed in Japanese Laid-Open Patent Application 2001-101777, there is the risk that the base plate strength and hermetic seal will be diminished. To solve this problem, there is also a known technique in which a base plate is provided with a plurality of coded protrusions, or letters are written in relief to display the model name, etc.
When a model name or the like is coded and written in relief on a base plate, the model name is determined by image recognition technology using an image recognition apparatus prior to precision machining However, noise tends to be picked up due to the effects of surface irregular reflection or the like, and solving this problem requires fine adjustment of the image recognition apparatus. Also, in the case of letters, misrecognition is inevitable because of factors such as blurring due to wear of the stamper.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved a method for manufacturing a base member. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.